To ensure normal production and operation of fluid channels (generally referred to as flow channels) of gas wells, oil wells, water wells, gas pipelines, oil pipelines, water pipelines, pipe fittings, instruments, etc. and to solve a production problem or achieve a production purpose, it is generally necessary to add functional chemical agents (commonly known as drugs) to the flow channels and facilities, which is commonly known as drug dosing. For example: to ensure that no hydrate blockage is formed in the gas wells and the gas pipelines, the method of adding hydrate inhibitors such as methanol, etc. is generally adopted in China; to reduce corrosion and scaling of the gas pipelines, the oil pipelines, the water pipelines and the pipe fittings, the method of adding corrosion inhibitors, scale inhibitors and bactericides is generally adopted in China; to solve the problem of the influence of physical properties of crude oil on the production of the oil wells, auxiliaries for oil extraction such as viscosity reducer, pour point depressants, paraffin removers, etc. are generally added to the oil wells in China; to solve the problem of oil-water separation, demulsifiers are generally added to crude oil pipelines or dehydrators in China; to treat oilfield sewage, flocculating agents and degreasing agents are generally added to sewage pipelines or sewage treatment systems in China; and so on.
Because the flow channels of the gas wells, etc. have fluids with higher pressure and the pressure of some fluids is even above 20 MPa, it is necessary to adopt a specific drug dosing device and drug dosing method for adding the functional chemical agents to the flow channels.
At present, a drug dosing device and a drug dosing method used for the flow channels in China include a drug dosing method of a metering pump, and a drug dosing method of a drug dosing canister (commonly called a drug dosing pack); the drug dosing method of the drug dosing canister is also classified into a periodic drug dosing method of a small drug dosing canister and a continuous drug dosing method of a balance type drug dosing canister (commonly called a drug dosing method of a gravitation canister); and the above drug dosing methods have different defects.
The Drug Dosing Method of the Metering Pump:
The method uses the metering pump for adding the functional chemical agents to the flow channels, and has the following defects:
1) The method has larger energy consumption and larger fixed investment, and needs to construct a special drug dosing pump house or a mobile drug dosing device.
2) The method often needs to pave a long-distance drug dosing pipeline, causing enormous investment of ground construction.
Taking a Jingbian gas field as an example, a gas well and a well site have no commercial power supply. To add methanol to ground pipelines of the gas well and the well site, the method of constructing a special methanol injecting pump house and a long-distance methanol injecting pipeline is generally used currently; and the methanol injecting pipeline has a general length of 1000 m to 5000 m, causing enormous ground investment.
3) The method cannot meet the production need of the gas well when solar energy is used for power supply.
Taking the Jingbian gas field as an example: the gas well of the gas field needs to add the methanol continuously for all-weather 24 hours; and if continuous cloudy and rainy weather appears, a solar panel cannot effectively supply power for the metering pump.
4) The metering pumps such as plunger pumps, diaphragm pumps, etc. used in the method have moving components, are extremely easy to generate operation fault, and need higher energy consumption and operation and maintenance cost for maintaining operation.
The Periodic Drug Dosing Method of the Small Drug Dosing Canister:
The method periodically adds the functional chemical agents to the flow channels of the gas well, the oil well, the oil and gas pipelines, etc., by using a drug dosing canister with the effective volume of less than 10 L. As shown in FIG. 1, the drug dosing device generally comprises a drug dosing canister 100, a drug dosing pipeline 101, an upper valve 102, a lower valve 103 and a bell mouth 104. The drug dosing canister 100 used in the method has lighter weight, is generally vertically installed on the upper part of a flow channel 105, and can enable the functional chemical agents in the drug dosing canister 100 to automatically flow into the flow channel 105 via self gravity. The method has the following defects:
1) the drug dosing canister used in the method has small effective volume, is not provided with a pressure balance pipe, cannot satisfy the production need of continuous drug dosing for all-weather 24 hours to the flow channels of the gas well, the sleeve of the oil well, a natural gas pipeline, etc., and only can be used for periodic drug dosing of the flow channels.
It is known from the common knowledge in the art that: as shown in FIG. 1, the drug dosing canister 100 in the periodic drug dosing method of the small drug dosing canister has no pressure balance pipe; if the drug dosing pipeline 101 below the drug dosing canister 100 has a small inner diameter or the degree of opening of the lower valve 103 is very small, when the drug in the drug dosing canister 100 automatically flows into the flow channel 105, it is difficult for gas in the flow channel 105 to rise and enter the drug dosing canister 100, and the drug dosing canister 100 will form certain vacuum degree, which causes that the drug in the canister cannot automatically flow into the flow channel 105; and if the drug dosing pipeline 101 below the drug dosing canister 100 has a larger inner diameter or the degree of opening of the lower valve 103 is larger, the chemical agent in the drug dosing canister 100 will soon flow into the flow channel 105, which causes that it is difficult to achieve the purpose of continuous drug dosing.
It is known from the common knowledge in the art that: the functional chemical dosage added to the gas well or natural gas pipeline is generally large; for example, in the Jingbian gas field, every day methanol is added to the gas well or a gas gathering pipeline with 30-200 L/day; the drug dosing canister with the effective volume of less than 10 L can only be used for periodic drug dosing of the gas well and the natural gas pipeline; for example, in a Sulige gas field, the drug dosing canister with the effective volume of less than 10 L is used once for periodically adding the methanol to an oil pipe of the gas well, and the natural gas pipeline of the well site; and no data and application paradigm are disclosed currently in China about the use of the drug dosing canister of which the effective volume is less than 10 L for continuous drug dosing for all-weather 24 hours to the gas well and the natural gas pipeline.
It is known from the common knowledge in the art that: a domestic oil well often uses the drug dosing canister with the effective volume of less than 10 L for periodically adding the viscosity reducer and the corrosion inhibitors to the oil pipe of the oil well; and there is no data and application paradigm disclosed currently in China about the use of the drug dosing canister with the effective volume of less than 10 L for continuous drug dosing for all-weather 24 hours to the oil pipe of the oil well.
It is known from the common knowledge in the art that: the metering pumps are generally used in China for adding the corrosion inhibitors and the scale inhibitors to the water pipelines; and there is no data and application paradigm disclosed currently in China about the use of the drug dosing canister with the effective volume of less than 10 L for continuous drug dosing for all-weather 24 hours to the water pipelines.
2) Before the drug dosing canister is used in the method for drug dosing to the flow channel every time, the gas in the drug dosing canister must be first emptied, so the method not only has potential safety hazard, but also has large labor intensity.
As shown in FIG. 1, after the chemical agent in the drug dosing canister 100 is exhausted, the upper valve 102 of the drug dosing canister must be opened, and after the gas in the drug dosing canister 100 is emptied, a new chemical agent is added to the drug dosing canister 100. Then the upper valve 102 of the drug dosing canister 100 must be closed and the lower valve 103 of the drug dosing canister must be opened, so that the chemical agent in the drug dosing canister 100 automatically flows into the flow channel 105.
It is known from the common knowledge in the art that: most of the functional chemical agents (e.g., methanol) are harmful for human bodies, and operators may be hurt when the gas in the drug dosing canister is accidentally emptied.
3) The drug dosing canister of the method is not provided with a level gauge and a flowmeter, and the flow of the functional chemical agents flowing from the drug dosing canister cannot be metered. The operators can only judge the liquid level of the drug dosing canister by virtue of individual feelings and experience, and can only control the flow of the functional chemical agents by virtue of personal experience.
It is known from the common knowledge in the art that: there is no practical application significance for the drug dosing canister with the effective volume of less than 10 L to be provided with the level gauge and the flowmeter, and there is no application paradigm and disclosed data of installing the level gauge and the flowmeter on the drug dosing canister with the effective volume of less than 10 L currently in China.
The Continuous Drug Dosing Method of the Balance Type Drug Dosing Canister:
the method uses the drug dosing canister with the effective volume of greater than 10 L and the pressure balance pipeline for continuously adding the functional chemical agents to the flow channels. As shown in FIG. 2, the drug dosing device generally comprises a drug dosing canister 200 (having a level gauge 201), a bracket 202, a drug dosing pipeline 203, a pressure balance pipeline 204, a flowmeter 205 and a valve 206. The drug dosing canister 200 of the method has heavier weight, is difficult to be directly vertically installed on the flow channel 207 and is generally installed near the gas well, the oil well and the pipeline. The working principle and the drug dosing process of the method are: making the height of the bottom of the drug dosing canister 200 higher than that of the flow channel 207 by using the bracket 202; communicating the bottom of the drug dosing canister 200 with the flow channel 207 by using the drug dosing pipeline 203; communicating the upper part of the drug dosing canister 200 with the flow channel 207 by using the pressure balance pipeline 204; the pressure in the drug dosing canister 200 realize a balance with the pressure in the flow channel 207; and the chemical agent in the drug dosing canister 200 can automatically flow into the flow channel 207 via self gravity. The method has the following defects:
1) Although the drug dosing canister 200 of the method is provided with the level gauge 201, the designed level gauge 201 is only used for displaying the height of the liquid level (commonly called a canister level) in the drug dosing canister and cannot meter, display and control the flow of the chemical agent flowing from the drug dosing canister.
The disclosed data shows that: the level gauge disposed on the container (canister) is used for displaying the height of the liquid level in the container (canister), and no disclosed data shows that the level gauge disposed on the container (canister) can be used for metering and displaying the flow of the liquid flowing from the container (canister) currently. There is no disclosed data and application paradigm in the art currently about the use of the level gauge disposed on the drug dosing canister for metering, displaying and controlling the flow of the chemical agent flowing from the drug dosing canister.
2) When the flow of the functional chemical agent (commonly called a drug dosing flow) flowing from the drug dosing canister 200 used in the method is smaller, the flow is less than the minimum range of a currently known flowmeter in China, causing that the drug dosing flow which flows from the drug dosing canister cannot be metered and the actual need of continuous drug dosing cannot be satisfied.
It is known from the common knowledge in the art that: when the minimum ranges of various known flowmeters used currently in the domestic continuous drug dosing method of the balance type drug dosing canister exceed 2.5 L/hr (being equivalent to 60 L/day), the drug dosing flow less than 2.5 L/hr cannot be effectively metered.
Taking the Jingbian gas field as an example: the gas field adopts a production process of continuously adding the methanol to the gas well (or the gas gathering pipeline) for 24 hours, and the drug dosage of the methanol is generally 30-200 L/day, being equivalent to the drug dosing flow of 1.25-8.3 L/hr.
Taking a Yanchang gas field as an example: the gas field adopts a production process of continuously adding the hydrate inhibitors to the gas well (or the gas gathering pipeline) for 24 hours, and the drug dosage of the hydrate inhibitors is generally 5-30 L/day, being equivalent to the drug dosing flow of 0.2-1.25 L/hr.
The disclosed data shows that: current kinds of flowmeters used for liquid metering are classified into a volumetric flowmeter (e.g., a gear meter, a waist wheel flowmeter, a rotating piston flowmeter and a scraper flowmeter), a vane wheel type flowmeter (e.g., a water meter and a turbine flowmeter), a differential pressure flowmeter, a variable-area flowmeter (e.g., a float flowmeter and a rotor flowmeter), a momentum type flowmeter, an impulse type flowmeter, an electromagnetic flowmeter, an ultrasonic flowmeter, a fluid oscillation type flowmeter (e.g., a vortex street flowmeter and a vortex flowmeter) and a coriolis mass flowmeter, all of which need to install a filter.
It is known from the common knowledge in the art that: when the minimum ranges of the current domestic gear meter, the waist wheel flowmeter, the rotating piston flowmeter and the scraper flowmeter are 40 L/hr (being equivalent to 960 L/day) and the minimum ranges of the water meter and the vortex flowmeter are 30 L/hr (being equivalent to 720 L/day), the ranges and precision are directly related to the viscosity of a measured liquid; the functional chemical agents have an enormous viscosity difference; for example, the viscosity of the viscosity reducer and foaming agents is hundreds of times of the viscosity of the methanol and the scale inhibitors; if such flowmeters are used for metering the flow of the functional chemical agents, each chemical agent is required to be checked and calibrated again; for example, when the water meter is dispatched from the factory, the range and the precision are calibrated with clean water; when the water meter is used for metering the viscosity reducer and the foaming agents, a dial or secondary display meter thereof must be recalibrated; otherwise, an enormous metering error may be generated; therefore, such flowmeters cannot meter the drug dosing flow of the gas well of the Jingbian gas field with a methanol flow of 30-200 L/day, and cannot meter the drug dosing flow of the gas well of the Yanchang gas field with a filling flow of the hydrate inhibitors of 5-30 L/day.
It is known from the common knowledge in the art that: the differential pressure flowmeter needs to use a throttle for generating differential pressure, and the range and the precision thereof are directly related to the viscosity and the density of the measured liquid; the continuous drug dosing method of the balance type drug dosing canister relies on gravity for automatic flowing and drug dosing; the generated differential pressure is very limited, so the differential pressure required for the differential pressure flowmeter cannot be satisfied and effective metering cannot be performed; the functional chemical agents have an enormous viscosity difference and an enormous density difference; for example, the density of the methanol is 0.8 g/cm3, the density of the scale inhibitors can reach 1.1 g/cm3 and the density of the hydrate inhibitors can reach 1.5 g/cm3; if such flowmeters are used for metering the flow of the functional chemical agents, each chemical agent is required to be checked and calibrated again; otherwise, an enormous metering error may be generated; therefore, such flowmeters cannot meter the drug dosing flow of the gas well of the Jingbian gas field with a methanol flow of 30-200 L/day, and cannot meter the drug dosing flow of the gas well of the Yanchang gas field with a filling flow of the hydrate inhibitors of 5-30 L/day.
It is known from the common knowledge in the art that: the momentum type flowmeter, the impulse type flowmeter, the vortex street flowmeter the vortex flowmeter, and the coriolis mass flowmeter require that the flowing speed of a measured medium is not too low, and the vortex street flowmeter and the vortex flowmeter also require that the flowing speed of the measured medium must be greater than the flowing speed of a laminar flow. the ranges and the precision of such flowmeters are directly related to the viscosity and the density of the measured liquid; if such flowmeters are used for metering the flow of the functional chemical agents, each chemical agent is required to be checked and calibrated again; otherwise, an enormous metering error may be generated; a current domestic known drug dosing pipeline has an inner diameter of 10 mm and the flowing speed with a methanol flow of 30 L/day is 4.4 mm/s, so the requirement of the minimum flowing speed of the measured medium required for such flowmeters cannot be satisfied and effective metering cannot be performed; therefore, such flowmeters cannot meter the drug dosing flow of the gas well of the Jingbian gas field with a methanol flow of 30-200 L/day, and cannot meter the drug dosing flow of the gas well of the Yanchang gas field with a filling flow of the hydrate inhibitors of 5-30 L/day.
It is known from the common knowledge in the art that: part of the functional chemical agents is an organic liquid; for example, the methanol is an insulator; the electromagnetic flowmeter requires that the measured medium must have certain conductivity; therefore, the electromagnetic flowmeter cannot effectively meter the methanol flow.
It is known from the common knowledge in the art that: the ultrasonic flowmeter has a resolution of 1 mm/s for the flowing speed, but cannot effectively meter the flow in a pipe with the inner diameter of less than 15 mm and the flowing speed of less than 10 mm/s; when the flow of the liquid of which the inner diameter of the pipeline is 15 mm and the flowing speed is 10 mm/s is 6.4 L/hr, which is equivalent to 153.6 L/day; therefore, the ultrasonic flowmeter cannot meter the drug dosing flow of the gas well of the Jingbian gas field with a methanol flow less than 150 L/day, and cannot meter the drug dosing flow of the gas well of the Yanchang gas field with a filling flow of the hydrate inhibitors of 5-30 L/day.
It is known from the common knowledge in the art that: the range and the precision of the float flowmeter (i.e., the rotor flowmeter) are directly related to the measured liquid, and are calibrated with clean water when dispatched from the factory; if the float flowmeter is used for metering the flow of the functional chemical agents, each chemical agent is required to be checked and calibrated again; otherwise, an enormous metering error may be generated; therefore, when the minimum range of the current domestic known float flowmeter is 2.5 L/hr (being equivalent to 60 L/day), the float flowmeter cannot meter the drug dosing flow of the gas well of the Jingbian gas field with a methanol flow less than 60 L/day, and cannot meter the drug dosing flow of the gas well of the Yanchang gas field with a filling flow of the hydrate inhibitors of 5-30 L/day.
It is known from the common knowledge in the art that: a tilting metering separator is often used for metering produced liquid of the oil well, has a minimum range of 1000 L/day, cannot meter the drug dosing flow of the gas well of the Jingbian gas field with a methanol flow of 30-200 L/day, and cannot meter the drug dosing flow of the gas well of the Yanchang gas field with a filling flow of the hydrate inhibitors of 5-30 L/day. There is no application paradigm or disclosed data currently in China about the tilting metering separator of which the minimum range is less than 1000 L/day.
It is known from the common knowledge in the art that: a tilting metering device for metering rainfall exists currently in China, but the device cannot be used for metering the flow of the liquid in the flow channels of pipelines, etc.; and there is no application paradigm or disclosed data currently in China about the use of such device for metering the flow of the liquid in the flow channels.
3) When the drug dosing flow which flows from the drug dosing canister 200 used in the method cannot be metered by the flowmeter 205, the method can only realize control of the drug dosing flow depending on the change value of the liquid level displayed by the level gauge 201 of the drug dosing canister 200 in unit time through a method of manually controlling the degree of opening of the valve 206, inevitably causing extremely slow control work of the drug dosing flow, so the needs of the flow channels for production and operation cannot be satisfied.
It is known from the common knowledge in the art that: because of large fluctuation of various production parameters (e.g., fluid flow, pressure, temperature, etc.) of the flow channels, the production parameters cannot be constant; environmental temperature and ground temperature cannot be constant; the flow of the functional chemical agents continuously added to the flow channels is inevitably often controlled; and the control of the drug dosing flow (or drug dosage) is an important and frequent working content in management of the flow channels of the gas wells, the oil wells, the pipelines, etc.
Taking the Jingbian gas field as an example: the methanol is continuously added for 24 hours to most of the gas wells and the natural gas pipelines of the gas field for inhibiting the formation of natural gas hydrates; the capability of the methanol for inhibiting the formation of the hydrates is directly related to the production parameters of gas yield, water yield, pressure, temperature, etc. of the gas well; if the water yield of the gas well is suddenly increased, or the pressure of the gas well is suddenly increase, or the gas yield of the gas well is suddenly decreased, or the ground environmental temperature is suddenly decreased, the quantity of the methanol continuously added to the gas well and the natural gas pipeline must be increased as soon as possible; otherwise, the hydrates may be formed, blocking the gas well and the natural gas pipeline.
It is known from the common knowledge in the art that: the continuous drug dosing method of the balance type drug dosing canister adopts a manual method for controlling the drug dosing flow, i.e., increasing or decreasing the drug dosing flow according to the display of instantaneous flow data of the flowmeter on the drug dosing pipeline through a method of manually controlling the degree of opening of the valve; therefore, when the flowmeter on the drug dosing pipeline cannot effectively and accurately display an instantaneous drug dosing flow, the operators cannot use the flowmeter for controlling the degree of opening of the valve, and can only control the degree of opening of the valve according to the decreased value of the liquid level of the level gauge of the drug dosing canister in unit time; if the cross section area of the drug dosing canister is large and the drug dosing flow is small, the operators need a long time for controlling the valve to a required degree of opening and need a long time for controlling the drug dosing flow to a required flow.
Taking the Jingbian gas field in which the methanol is added continuously to the gas well in 1.25 L/hr (i.e., 30 L/day) as an example: to reduce the number of times and cost for supplementing the functional chemical agents into the drug dosing canister, the effective volume of the drug dosing canister shall not be too small, and a horizontal cylindrical drug dosing canister (with the effective volume greater than 180 L and the maximum cross section area of 0.6 m2) with an inner diameter of 400 mm and a length of 1500 mm can be adopted for continuously adding the methanol for 6 days to the gas well with the drug dosing flow of 1.25 L/hr (i.e., 30 L/day); a vertical cylindrical drug dosing canister (with the effective volume greater than 250 l and the cross section area of 0.5 m2) with an inner diameter of 800 mm and a height of 500 mm can also be adopted for continuously adding the methanol for 8 days to the gas well with the drug dosing flow of 1.25 L/hr (i.e., 30 L/day); and because the existing domestic known flowmeter cannot meter the flow of the methanol with the drug dosing flow of 1.25 L/hr (i.e., 30 L/day), the operators can only control the degree of opening of the valve according to the decreased value of the liquid level of the level gauge of the drug dosing canister in unit time. It is known from the common knowledge in the art that: when the reading change value of the level gauge is less than 5 mm, eyes of the operators or the ultrasonic level gauge is difficult to accurately judge the change of the liquid level; computed according to the decrease of 5 mm of the liquid level of the vertical cylindrical drug dosing canister with the inner diameter of 800 mm and the height of 500 mm, it is known from the computation of the common knowledge in the art that the functional chemical dosage which flows from the drug dosing canister is 3 L and the effluent time in accordance with the drug dosing flow of 1.25 L/hr is 2.4 hours; therefore, the operators need to wait for 2.4 hours after controlling the degree of opening of the valve so as to judge whether the controlled degree of opening of the valve is reasonable and judge whether the drug dosing flow is reasonable; because the operators have no guidance of flowmeter data and the control of the degree of opening of the valve inevitably has great blindness, the operators cannot control the degree of opening of the valve to a reasonable position within a short time only according to the indication of the level gauge, cannot control the drug dosing flow to a reasonable flow within a short time, and need a long time for successful control; and computed according to 3 times of control, the operators need to work for 7.2 hours to control the drug dosing flow to the required flow. It is known from the common knowledge in the art that: the condition that the production parameters of the gas well are greatly changed often occurs; if the gas well needs to increase the drug dosing flow of the methanol due to the change of the production parameters, the flow of the methanol cannot be increased to the required drug dosing flow of the gas well within 1 hour, causing a production accident that the gas wells and the pipelines are blocked by the hydrates; otherwise, if the gas well needs to decrease the drug dosing flow of the methanol due to the change of the production parameters, the flow of the methanol cannot be decreased to the required drug dosing flow of the gas well within 1 hour, causing the waste of the methanol and an increase of the production cost of the gas well; therefore, the method of manually controlling the drug dosing flow greatly increases the labor intensity of the operators, brings great difficulty to management of the gas well and cannot satisfy the production need of quickly controlling the drug dosing flow required by the flow channels of the gas well, the pipeline, etc.
Taking the Yanchang gas field in which the hydrate inhibitors are added continuously to the gas well in 0.5 L/hr (i.e., 12 L/day) as an example: to reduce the number of times and cost for supplementing the drugs into the drug dosing canister, the effective volume of the drug dosing canister shall not be too small, and a horizontal cylindrical drug dosing canister (with the effective volume greater than 180 L and the maximum cross section area of 0.6 m2) with an inner diameter of 400 mm and a length of 1500 mm can be adopted for continuously adding the hydrate inhibitors for 15 days to the gas well with the drug dosing flow of 0.5 L/hr (i.e., 12 L/day). It is known from the common knowledge in the art that: when the reading change value of the level gauge is less than 2 mm, eyes of the operators or the ultrasonic level gauge is difficult to accurately judge the change of the liquid level; computed according to the decrease of 2 mm with the maximum cross section area of 0.6 m2 for the liquid level of the horizontal cylindrical drug dosing canister with the inner diameter of 400 mm and the length of 1500 mm, the functional chemical dosage which flows from the drug dosing canister is 1.2 L and the effluent time in accordance with the drug dosing flow of 0.5 L/hr is 2.4 hours; therefore, the operators need to wait for 2.4 hours after controlling the degree of opening of the valve so as to judge whether the controlled degree of opening of the valve is reasonable and judge whether the drug dosing flow is reasonable; because the operators have no guidance of flowmeter data and the control of the degree of opening of the valve inevitably has great blindness, the operators cannot control the degree of opening of the valve to a reasonable position for one time only according to the indication of the level gauge, cannot control the drug dosing flow to a reasonable flow for one time only, and need many times of control; and computed according to 3 times of control, the operators need to work for 7.2 hours to control the drug dosing flow to the required flow. It is known from the common knowledge in the art that: the condition that the production parameters of the gas well are greatly changed often occurs; if the gas well needs to increase the drug dosing flow of the hydrate inhibitors due to the change of the production parameters, the flow of the hydrate inhibitors cannot be increased to the required drug dosing flow of the gas well within 1 hour, causing a production accident that the gas wells and the pipelines are blocked by the hydrates; otherwise, if the gas well needs to decrease the drug dosing flow of the hydrate inhibitors due to the change of the production parameters, the flow of the hydrate inhibitors cannot be decreased to the required drug dosing flow of the gas well within 1 hour, causing the waste of the hydrate inhibitors and an increase of the production cost of the gas well; therefore, the method of manually controlling the drug dosing flow greatly increases the labor intensity of the operators, brings great difficulty to management of the gas well and cannot satisfy the production need of quickly controlling the drug dosing flow required by the flow channels of the gas well, the pipeline, etc.
4) The flowmeter 205 designed in the method can only be used for metering the drug dosing flow, and cannot display the liquid level of the drug dosing canister.
In conclusion, the above drug dosing device and the drug dosing method thereof are not convenient for drug metering and control in case of adding the functional chemical agents in a small flow.